A woman’s claim in a Facebook posting that her ex-husband “tried to strangle” her was not libellous because there was evidence of an attack, the supreme court has been told.

In an extraordinary case involving a bitter domestic dispute, five of the UK’s most senior judges are being asked to decide whether the phrase meant he had attempted to kill her and was therefore defamatory.

The appeal has been brought by Nicola Stocker, who divorced her husband, Ronald, in 2012. Shortly afterwards, she requested and was accepted as a Facebook friend by his new partner, Deborah Bligh.

During a series of exchanges with Bligh, Stocker told her about her former husband, saying: “Last time I accused him of cheating, he spent a night in the cells, tried to strangle me.” The posting was seen by several other acquaintances online.

In written submissions to the court, David Price QC, for Nicola Stocker, argued that: “The phrase ‘tried to strangle’ is a common way of describing an assault involving a constriction of the neck or throat where the victim is alive … The phrase does not convey an intent to kill in ordinary language or in relevant criminal offences.”

Both the high court and the court of appeal, however, found in favour of Ronald Stocker’s defamation claim against his ex-wife on the grounds that the words “tried to strangle” did imply an attempt to kill her by strangulation.

But Mr Justice Mitting also ruled that Mr Stocker had “in temper” placed one hand on her mouth and the other on her neck in order to silence her with such force that red marks were visible on her neck to the police in an interview two hours later.

Nicola Stocker was ordered to pay £5,000 damages plus legal costs in the high court case. Following an unsuccessful appeal to the court of appeal, her legal costs are estimated to have escalate to more than £200,000. “The [high court] judge’s finding that ‘tried to strangle’ logically imputed an intent to kill (based on the two Oxford English Dictionary definitions of strangle and the fact that the appellant was alive with red marks on her neck) was wrong,” Price told the court in written submissions.

“If the judge’s meaning is overturned, it must follow that the defence of justification succeeds on the basis of the proved and admitted facts.”

Protesters supporting Nicola Stocker gathered outside the supreme court on Thursday morning. The human rights organisation Liberty warned that the case raised concerns that victims of domestic abuse could be silenced by the use of defamation laws.

Before the case, Harriet Wistrich, the director of the Centre for Women’s Justice, said: “This case has chilling implications for women who speak out about male violence. The judgment reveals a shocking ignorance amongst members of the judiciary of the realities of domestic violence.

“The fact that Mr Stocker was arrested and red marks were observed by the police on the victim’s neck is a serious warning of escalation of violence regardless of whether he had any intent to kill.

“In fact, strangulation is a warning marker in standardised police risk assessments. We are appalled that a woman speaking out about an accepted incident of domestic violence has been silenced and severely financially penalised.” Karen Ingala Smith, the co-founder of the Femicide Census, said: “We know …. that between 2009 and 2017, 285 women were killed though strangulation, of which 188 women were strangled to death by a current or former partner; that’s an average of one woman strangled to death every two weeks. It is the second most common method used to kill women in the UK.

“Whether used as a means to kill, frighten and/or control women strangulation is extremely dangerous and abusive.”